The present invention pertains to a sewing machine having a control shaft for operating the machine's needle and with said control shaft being connected, via transmission means, to an operating motor of the clutch and brake type that includes means for selectively effecting rotation or the braking of said control shaft. The sewing machine is further provided with a needle positioning device comprising means for effecting selective positioning of the needle which is operatively connected to the control shaft and an auxiliary actuator is adapted to cause the necessary movement of said control shaft as is necessary for positioning the needle. A unidirectional auxiliary transmission or clutching means is located between the auxiliary actuator and the selective positioning means and is adapted to transmit the rotational movement of the auxiliary actuator to the control shaft and by locating elements operatively associated with said selective positioning means the needle can be stopped in a preselected position.
Sewing machines of the type described above are well known in the sewing art; however, the associated needle positioning device which is utilized with them is considered to increase the overall cost of such machines by an excessive amount.
The majority of research efforts in this field have been mainly directed towards attempts to simplify these positioning devices in order to reduce their cost and thereby lessen the overall cost of the sewing machine. The most common result of this work has been the separation from the operating motor of the auxiliary actuator which is necessary for moving the control shaft during the operation of positioning the needle to a desired and predetermined position.
In practice, however, provision of separate and independent auxiliary actuating means has not provided completely satisfactory results for use has been made of actuating means which are considered to be bulky and cumbersome such as for example pneumatic units provided with a control rack and an associated pinion on the transmission apparatus for the positioning device.
An object of the present invention is to provide a sewing machine, having a conventional and well known type of clutch brake motor with a needle positioning device of simplified construction, relatively inexpensive to manufacture, reliable in operation and which can be assembled on new and existing sewing machines without modifications thereto.